Fiber-reinforced ceramic composites are materials which have many utilities and are used, e.g., for aeronautical applications, radome protection, draw rollers for synthetic filaments, and tools. However, such composites as normally prepared are porous materials which have less strength than is sometimes desired.
Copending application S.N. (Case CE-6102-B) (Yu et. al.) teaches that the density and strength of these composites can be increased by (A) infiltrating them with a crosslinkable preceramic composition comprising about 40-70% by weight of a low molecular weight polysilazane, about 15-35% by weight of a medium molecular weight polysilazane, and about 5-30% by weight of an unsaturated organic or organosilicon compound containing at least two alkenyl groups and (B) heating the infiltrated composite to pyrolyze the infiltrant.
As discussed by Yu et. al., such infiltrants have lower viscosities and higher ceramic yields than conventional polysilazanes, such as the polysilazanes of U. S. Pat. Nos. 4,297,828 (Seyferth et. al.-I), 4,482,669 (Seyferth et. al.-II), 4,645,807 (Seyferth et. al.-III), 4,650,837 (Seyferth et. al.-IV), 4,659,850 (Arai et. al.), and 4,869,854 (Takeda et. al.).